fs_seek

int fs_seek(struct fs_file *file, uint32_t offset)

Positions a file's read and write pointer at the specified offset. The offset is expressed as the number of bytes from the start of the file (i.e., seeking to offset 0 places the pointer at the first byte in the file).

Arguments

Argument	Description
file	Pointer to the file to reposition
offset	The 0-based file offset to seek to

Returned values

• 0 on success
• FS error code on failure

Notes

If a file is opened in append mode, its write pointer is always positioned at the end of the file. Calling this function on such a file only affects the read pointer.

Header file

#include "fs/fs.h"

Example

The following example reads four bytes from a file, starting at an offset of eight.

int
read_part1_middle(void)
{
    struct fs_file *file;
    uint32_t bytes_read;
    uint8_t buf[4];
    int rc;

    rc = fs_open("/data/parts/1.bin", FS_ACCESS_READ, &file);
    if (rc == 0) {
        /* Advance to offset 8. */
        rc = fs_seek(file, 8);
        if (rc == 0) {
            /* Read bytes 8, 9, 10, and 11. */
            rc = fs_read(file, 4, buf, &bytes_read);
            if (rc == 0) {
                /* buf now contains up to 4 bytes of file data. */
                console_printf("read %u bytes\n", bytes_read)
            }
        }

        /* Close the file. */
        fs_close(file);
    }

    return rc == 0 ? 0 : -1;
}